JP2004-204863A discloses a piston structure of a shock absorber. As illustrated in FIG. 8, this piston P1 is provided with an annular disc D that is held by a piston rod R inserted into a cylinder C, and a cylindrical skirt portion S that projects in the axial direction from the outer periphery portion of the lower end of the disc D (downward direction in FIG. 8).
The length of the piston P1 in the axial direction is obtained by adding the length of the disc D and the length of the skirt portion S. This makes it possible to reduce contact pressure with respect to the inner periphery of the cylinder C, at the time when lateral force is applied to the piston P1, as compared with the case where the length is for the disc D only.
The piston P1 is provided with an annular valve V on the inner side of the skirt portion S. Thereby, projection length of a piston nut N that keeps the annular valve V in contact with the disc D can be reduced, and correspondingly, an effective stroke of the piston P1 inside the cylinder C can be increased.